Upsetting-die lubricant for application to bolt stock or the like



Patented Nov. 28, 1950 UPSETTING-DIE LUBRICANT i on ArrLIoA- 'rIoN 'roBoL rs'rocK on THE LIKE Charles G. Canney, Worcester, Mass.,assignor toThe American Steel and Wire Company of New Jersey, a corporation of NewJersey No Drawing. Application May 29, 1946, Serial No. 673,175

. 2 Claims.

This invention relates to improvements in lubricants for bolt stock tobe subjected to cold upsetting.

In the manufacture of bolts, screws, rivetsand the like on cold headingmachines, it is essential that the wire or rod from which such productsare fabricated have a coating which will protect the tools of theheaders, notably dies, from rapid or excessive wear by preventing directcontact of metal against metal.

In practice, it is essential that this coating fulfillcertainrequirements. For example the coating should not clog the dies, norbecome impregnated with foreign particles of an abrasive nature from thetime the wire is made until it is used. Additionally, the coating musthave the necessary lubricating qualities for wire drawing and headingdie extrusion, and it must remain stable under varying conditions oftemperature and humidity, and not decompose over long periods of time.Furthermore, the coating must act as an anti-rust agent with respect tothe wire surface and also with respect to surfaces of the products fromcold heading machines which are to be subjected to further processing ata later date, and

it must be easily removable from the surface of the formed products inpreparation for plating while not leaving any foreign residue whichrequires excessive effort to remove after the headed capable ofpowdering away to a certain degree under deformation.

1 have invented a lubricant which satisfies the above requirements and amethod of processing wire by the aid thereof. According to my invention,the wire is prepared in the following manner and sequence, expressedfirst in general terms, to be elaborated upon hereinafter. The generalsequence of operations is:

1. Wire or rods are cleaned to remove scale, grease, or other foreignmatter, following which a 2. light or heavy sull coat is applied,depending on the number of drafts to be made. Then a 3. light or heavylime coating is applied, depending on the number of drafts to be made.

Next 4-, the coated rods or wire are dried, afterwhich v 5. thethus-coated rods or wire are drawn to finish size through a novellubricant consisting of a mixture of grease identified as No. 2consistency, and hydrated lime. The end result is a wire or rod surfaceon which is a layer of sull adjacent to the surface of the wire or rod,changing gradually to an external surface of asiillgrease-limecomposite, comprising a very thin, brown, hard, glossy, tightly bondedcoat.

The lubricant referred to in (5) above is composed of from approximatelyten per cent to approximately thirty per cent of No, 2 consistencygrease, and from approximately seventy per cent to approximately ninetyper cent of fortifying agent, which may be lime, such as hydrated lime,borax, or hydrated lime mixed with graphite.

The No. 2 consistency grease referred to above is composed ofapproximately eighty-five per cent mineral oil and fifteen per centsoaps. To make the soap a definite amount of fats and fatty acids aresaponified to soap by a converting agent, such 'as soda ash, or thecarbonates or hydroxides of the alkali metal group or hydroxides of thealkaline earth metals, the saponification being carried out by heatingthe mixture of fats andsaponifying agent. The mineral oil and soap thenare added together with agitation and heating until the soap dispersesthroughout the mineral oil in a homogeneous colloidal suspension. Oncooling down, the resulting mass becomes gelatinous and forms thelubricating grease herein referred to. However, instead ofsaponifyingfats and fatty acids and mixing the resulting soap with themineral oil in two steps, the mineral oil is mixed with the fats andfatty acids and the latter saponified in the presence of the mineral oilin a single kettle under elevated temperature and pressure to effect thecolloidal dispersion of the soap in a single kettle, rather than tosaponify in one kettle and suspend in another without the medium ofpressure.

The following are some of the factors that influence the melting point,penetration value, and texture of the resulting grease: 1) thetemperature. and pressure employed during manufacture; (2) the physicaland chemical characteristics of the fats and fatty acids employed; and(3) the amount of soap combined with the oil. Thus, in the manufactureof greases, it is possible to have melting points up to 600 F., orpenetration values down to 0. It is a matter of material selection andmethod of preparation.

The mineral oil employed in the production of No. 2 consistency greasehas a gravity of 24 B., flash point,340 F., fire point395 F., viscosity3 150 seconds Saybolt at 100 F. The properties and make-up of the No. 2consistency grease are as follows:

Penetration 265-290 Melting point, (approx.) F 195 Moisture percent-..1-1.5 Free fatty acid do 0.2 Soap do Mineral oil do 85 Referring morespecifically to steps 1 through 5, above, these generally expressedsteps may be defined more specifically as follows, the steps beingnumbered to correspond with each step as numbered above:

1. Rods or wire first are cleaned in the conventional manner, such as inhot sulphuric acid maintained at a temperature of from 160 F. to 190 F.Instead of sulphuric acid, hot or cold hydrochloric acid may be used inthe cleaning operation.

2. A sull coat then is applied to the wire, which may be either a lightsull or a heavy sull. A light sull is applied by subjecting the wire toan atomized water spray for about twenty minutes. Such a sull coat willpersist for two or three drafts of wire drawing. A heavy sull coat isapplied to the wire by subjecting the wire to an atomized water sprayfor about sixty minutes. Such a heavy sull coat will persist on the wirefor four or more drafts of wire drawing.

3. The sull coated rods or wire are then dipped in a bath of hot limemaintained at a temperature of from 180 F. to 200 F. This lime bath isan emulsion containing from four to five per cent lime and the restwater. The rods or wire are dipped in this lime bath for from one to twominutes. A heavy lime coat may be applied if desired by dipping the rodsin a lime bath containin from approximatel seven per cent toapproximately eight per cent lime and the remainder water, forapproximately the same period of time.

4. The lime coated rods are removed from the lime tub and allowed todrip ofi, after which they are dried in a flash baker for five or tenminutes. If desired, the lime coated rods may be baked in a conventionalbaker which requires from three to four hours.

5. The rods or wire then are drawn through a die using the wirelubricant described above. The wire, after it is drawn a sufficientnumber of drafts, will have an amount of lubricant coated on its surfaceso as to give a desired predetermined finish.

This is a desirable quality in that it disperses any excess lubricant orthat which is not essential for lubricity by powdering away and avoidingany tendencies to load or pit hammer or heading dies.

In the above-outlined procedure, step No. 2 provides for the applicationof a sull coat to the wire before it is dipped into the lime. Ifdesired, this sull coat may be eliminated, but it has been found thatwhen the sull coat is applied, the die life in the upsetting machines ispractically doubled as compared with the die life when using non-sullcoated rods or wire.

The coating or lubricant applied to the wire, as described above, hasthe following characteristics which are outstanding:

1. The coating or lu bricant has a pulverizing or flaking ability, thatis, the coatin will flake setting operation. This is a. desirablequality in 4. that it disperses the coating after it has performed itsfunction in protecting the upsetting dies so that it thereafter does notadhere to and clog up the dies.

2. The lubricant or coating has great mobility, that is, plasticity.

3. The lubricant has a, high surface tension which gives it a high filmstrength, that is, ability to resist friction. The lubricant has ahigher film strength than the so-called lacquo finish obtained inaccordance with the process of the United States Patent to Flint 0.Elder, No. 1,963,298, granted June 19, 1934.

4. The lubricant provides excellent protection against corrosion. Itaffords from approximately 400 to 500 per cent better protection againstcorrosion than is afforded by the lacquo finish described in the saidElder patent.

By virtue of my invention, the lime coating may be omitted in certaininstances, in which event, the rods or wire to be drawn are cleaned,sullcoated as described above, passed through the above-describedgrease-hydrated lime lubricant. and drawn.

If desired, coloring matter may be added to the lubricant to providedistinctive identifying colors for the stock. Thus, for example, theremay be incorporated in the lubricant from about three to eight per centof a dye material, the coloring however having no eifect on thelubricating value of the lubricating composition.

In general the most severe wear on dies, either full faced dies orrecessed faced dies, from the standpoint of critical tolerance area isthe area around the die hole, that is, from several thousandths of aninch outside the hole beyond the radius down into the hole below theradius several thousandths of an inch. Insertion of the blank into thedie may be made with a minimum of friction due to the smooth thinadherent coating. Such features of the coating also prevent blanks fromsticking in the die and also permits making of long shanked work Whereother lubricants would cause much difiiculty.

As the hammer delivers its blow, the blank effects a minute forwardtravel from the force of impact resulting in excessive frictionpotential on the die. It has been found that dies reach a constanttemperature of approximately F. The No. 2 consistency grease describedherein has a melting point approximately 45 higher than this, orapproximately F., thus avoiding any major changes in its physicalcondition, which, under higher temperatures, causes the grease to gofrom the solid to liquid state which reduces coating efficiency by filmstrength depreciation. In addition to protection provided from theradius down into the hole by the lubricant in the solid state at thisarea, the plasticity of the coating is also effective in providinglubrication in that the smooth coating is not broken or ruptured andalso permits extrusion of the shank. The condition of the coating atthis pointfurther enhance die life by reducing Wear on the first 0.0005inch of a new die hole where rapid opening is a normal expectancy of thesaid tolerance.

The area from the radius out on the face of the die or under the head ofthe work develops a relatively instantaneous temperature of 300 F. to400 F., which changes the grease into a very soft state. Lubricativeaction "Ts bolstered by the presence of lime and sull which wasincorporated in the coil described previously herein. In the case ofrecessed faced dies such physical condition is advantageous in that thecorners of the die do not load up with lubricant which results indesirable sharp corners on the headed part.

Being an extremely smooth continuous adherent coating, the inability ofmoisture to break down the finish permits unusual long periods ofwarehouse storage without added protection, such as paper wrapping.

While the invention is described in detail above, it is not desired tobe limited to the exact and specific materials and methods described, asthere may be used such substitutions, modificacations or equivalents, asare embraced within the scope of the invention as embraced in theappended claims.

I claim:

1. A wire drawing lubricant comprising from 70 to 90% hydrated lime andfrom to 30% of a grease composed of substantially eighty-five per centmineral oil and fifteen per cent soap, said oil having originally agravity of approximately 24 B., a fiash point of approximately 340 F., afire point of approximately 395 F., and a Saybolt viscosity of 150seconds at 100 F., the said grease having a penetration value of fromapproximately 265 to approximately 290, a melting point of approximately95 F., and a moisture content of from approximately 1 to 1.5 per cent.

2. A lubricant suitable for applying to bolt stock for lubricatingcold-heading dies, said lubricant consisting of from 10 to of a greasecomposed of a mineral oil and soap, the grease havin a melting point ofapproximately 195 F., and from to of a fortifying agent for the greaseselected from the group consisting of hydrated lime, hydrated lime mixedwith graphite, and boraX, said lubricant being capable of forming on thestock when drawn through a reducing die, a thin, hard, tightly adherentfilm which flakes 01f under the impact of the heading dies.

CHARLES G. CANNEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Elder Dec. 24, 1946

1. A WIRE DRAWING LUBRICANT COMPRISING FROM 70 TO 90% HYDRATED LIME ANDFROM 10 TO 30% OF A GREASE COMPOSED OF SUBSTANTIALLY EIGHTY-FIVE PERCENT MINERAL OIL AND FIFTEEN PER CENT SOAP, SAID OIL HAVING ORIGINALLY AGRAVITY OF APPROXIMATELY 24* BE., A FLASH POINT OF APPROXIMATELY 340*F.,A FIRE POINT OF APPROXIMATELY 395*F., AND A SAYBOLT VISCOSITY OF 150SECONDS AT 100*F., THE SAID GREASE HAVING A PENETRATION VALUE OF FROMAPPROXIMATELY 265 TO APPROXIMATELY 290, A MELTING POINT OF APPROXIMATELY195*F., AND A MOISTURE CONTENT OF FROM APPROXIMATELY 1 TO 1.5 PER CENT.